Hopes of finding survivors of the Christchurch earthquake seemed to be fading as the New Zealand authorities admitted they expected the death toll "to steadily rise" over the weekend.

Families were warned to prepare for the "worst type of news" after another day drew to an end with no sign of life beneath the rubble.

The death toll from Tuesday's 6.3-magnitude quake now stands at 144, with more than 200 missing, police said.

A multi-national team of more than 600 rescuers from New Zealand, the UK, the US, China, Taiwan, Japan, Mexico and Australia, continued scouring the devastated city on Saturday but recovered only bodies. Their efforts were hampered by a number of fresh aftershocks which sent masonry from a number of unstable buildings tumbling.

So far only six quake victims have been formally named, but police were continuing their attempts to identity the deceased. Christchurch mayor Bob Parker assured relatives of the missing that every effort was being made to locate any remaining survivors.

Among anxious British families waiting for news were relatives of Susan Selway, who was in her fourth-floor office in the Canterbury Television building in Christchurch on South Island when the tremors tore through the city earlier this week.

Ms Selway, a clinical psychologist who celebrated her 50th birthday this month, was working in the building temporarily after her previous office was badly damaged in the last earthquake to hit the area.

Friends and family of another missing Briton, Phil Coppeard, 41, also faced an agonising wait to learn what had happened to him. Mr Coppeard, who was last seen on a bus going in to Christchurch, emigrated to the country relatively recently with his wife Suzanne Craig.

Two Britons have been confirmed to be among the dead. British chef Gregory Tobin, 25, from Tadcaster, North Yorkshire, had been on an around-the-world trip and was believed to have been working temporarily at a garage in Christchurch when the devastation struck.

The identity of the other British victim, also male, has not been confirmed. British High Commission spokesman Chris Harrington said he believed seven UK nationals are on the missing list.